Sounds like you have a "Dual Header" A lot of vid cards (nearly all nowadays) have the facility for a second monitor/line out to TV etc. It can be quite useful too. I can only speak for myself, but I would just leave things as they are and if you ever need to hook up a second screen so that you can monitor TWO Pprune forums at once, then you now know how to do it.
Cheers,
Conan